Existing video tape recorders (VTRs) include a speed adjuster in their transport control. This adjuster varies linearly the rate of movement of a video tape through the transport. The control is usually a rotary shaft with no end stops which can be continuously rotated in either direction. The control may be used in two modes as follows:
1. Shuttle
This operation is performed with or without recorded images on the tape being displayed and is a fast wind or rewind operation. On entry into the mode, the transport is stationary. Progressive angular movement of the rotary shaft increases the linear speed of the tape and maximum speed can be achieved with less than .+-.180.degree. rotation. Rotation of the control back to its original position decreases the speed until it reaches its original position, whereupon the transport is stopped.
2. Job with Picture
In this mode, rotation of the shaft causes the tape to move forward linearly at a rate which is dependent upon the rate of shaft rotation. The shaft can be rotated slowly to up-date the video image frame by frame in a picture search operation or spun to advance or retard this tape at high speed. Forward and reverse movement of the tape is possible and the only limit on tape travel speed is the speed at which the operator can spin the shaft. The flywheel effect exhibited from system to system will vary depending upon the mass of the shaft and the friction in the system. However, to move the film a great distance the operator must continuously spin the shaft or revert to (1) shuttle operation. In this mode, the control system shaft can be regarded as an extension to the machine capstan motor.
The modes of operation described may also be applied to telecines and to other transport systems. Existing telecines incorporate a shuttle system similar to that described.